Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to cell reselection.
Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
As LTE networks largely overlap with W-CDMA networks, W-CDMA to LTE reselection speed is a concern for network operators. When a suitable LTE cell becomes available, it is preferable for a user equipment (UE) to reselect to a LTE cell as soon as the reselection conditions are met. However, the reselection to a LTE cell requires UE to first detect LTE cells. After detection of LTE cells, signal measurements such as reference signal received power (RSRP) and reference signal received quality (RSRQ) are performed. If RSRP and/or RSRQ criteria are met, the UE may trigger reselection to a LTE cell.
However, while performing signal measurements, a UE may transition from one priority scheduling mode to another priority scheduling mode, for example, from an all priority scheduling mode to a high priority scheduling mode or from a high priority scheduling mode to an all priority scheduling mode. The transition may be triggered due to changes in the UE's serving cell channel conditions.
In a high priority scheduling mode, a UE can generally set up a high priority detection timer according to 3rd generation partnership project (3GPP) Specifications. The high priority detection timer counts down as time goes by and the UE issues a search for a cell when the timer goes to zero, and resets the timer. A similar approach can be used in all priority scheduling mode. However, the 3GPP Specifications do not describe cell detection during mode transitions. If these current approaches are used, a mode transition may delay the cell detection process and, as a result, delay cell reselection.
Therefore, there is a desire for improved reselection during mode transitions at a user equipment.